This application relates generally to electrical power generation and, more specifically, to the optimization of energy storage device usage in wind energy applications.
A utility-scale wind energy system or wind farm includes a group of wind turbines that operate collectively as a power plant to produce electrical energy without the consumption of fossil fuels. The output of wind energy from a wind farm is less consistent than the energy output from fossil fuel-fired power plants. As a result, the power from wind turbines operating at nominal conditions in a wind farm may not meet output requirements for the power plant. For example, the power from a power plant may not track the power forecast due to forecast errors. As another example, the rate of power production for a power plant may be outside of a desired range because of wind gusts. A conventional approach for dealing with these and other similar situations is to use controls to manage the operation of the wind farm, such as utilizing pitch control of the rotor blades to increase or decrease the power produced by the individual wind turbines.
Traditional utility-scale wind energy systems are not dispatchable sources of electricity that can be turned on or off at the request of power grid operators. For that reason, a wind farm may include an energy storage device, such as one or more rechargeable batteries, that is linked to the power grid and that may assist with meeting requirements on the power production by the power plant. Energy storage systems can be used to shift power production by a wind farm from off-peak times to peak load times. Energy storage systems can store curtailed production for later release to the power grid. The ability to store energy during times of high wind turbine production and release the stored energy during times of low wind production also allows a wind farm to improve power production forecast accuracy. The accuracy improvements allow wind farms to meet firm capacity commitments to power companies and to avoid expensive penalties.
The pattern of charge and discharge cycles for intermittent generators, such as wind turbines, may be irregular dependent upon the application or combination of applications served by the wind farm. Nevertheless, a battery experiencing on average a single daily charge and discharge for twenty years in a wind farm accumulates roughly 7,300 cycles. As a result, candidate batteries of wind farms must be characterized by long cycle lifetimes. Battery life is dependent on both the depth of discharge and the rate of discharge, as well as other external factors such as temperature, charging strategy, etc.
Accordingly, the management of energy storage systems must be improved to optimize the use of energy storage systems, such as batteries, in wind energy applications.